Combined observations of rock mass movements using satelliteSAR interferometry, differential GPS, airborne digitalphotogrammetry, and airborne photography interpretation

摘要

Recent global warming, through the related retreat of mountain glaciers, causes agrowing number of different slope instabilities requiring accurate and cost-effectivemonitoring. We investigate the potential of combined remote sensing observationsfrom satellite and airborne microwave and optical sensors for an efficient survey ofmountainous ground displacements. The evolution of a paraglacial deep-seated rock massmovement due to glacier retreat in the Swiss Alps has been observed between 1976 and2008 with satellite synthetic aperture radar (SAR) interferometry, differential GPS,and airborne digital photogrammetry. Analysis of differential SAR interferograms revealedan acceleration of the landslide from —4 cm/yr in the slope-parallel direction during themid-1990s to more than 30 cm/yr in the summer of 2008. Differential GPS surveysperformed between the summers of 2007 and 2008 indicate seasonal variations of thelandslide activity. The photogrammetric analysis revealed no significant movement (i.e.,<1 cm/yr) between 1976 and 1995 and provides an overview of the total displacementbetween 1995 and 2006 with high spatial resolution. In situ and airborne photographyinterpretation suggests that the landslide was activated at earliest by the end of the LastGlaciation but without any significant long-lasting activity during the Holocene and thatthe exponentially increasing reactivation since the 1990s is the result of ongoingdebutressing of the valley flank due to the glacier retreat in combination with strongprecipitation and snowmelt events. We conclude that the employed remote sensingtechniques complement each other well within a landslide hazard assessment procedure.